A mortar is a muzzle-loading indirect fire weapon that fires shells at low velocities, short ranges, and high-arcing ballistic trajectories. A mortar is relatively simple and easy to operate. A modern mortar consists of a tube which gunners drop a shell into. A firing pin at the base of the tube detonates the propellant and fires the shell. These attributes contrast with the mortar's larger siblings, howitzers and field guns, which fire at higher velocities, longer ranges, flatter arcs, and sometimes, direct fire.
In order to fire the mortar, a firing solution is required having information such as temperature, type of rounds, type of tube, azimuth and elevation. In order to determine azimuth and elevation as well as current position, many methods have been used such as survey teams, using a magnetic compass, and sometimes even just an educated guess. Inaccurate and time consuming methods of firing leads to less combat power in a needed area and ultimately deaths of soldiers. A blast area of a mortar can be up to 50 m and injuries can happen outside that range. Accuracy and timeliness are imperative to the proper use of mortars.
Currently, there exists directional systems like MAPS® and TALIN® produced by Honeywell®. Items like the TALIN® can weigh twenty pounds or more and are not easily coupled to a mortar tube. The TALIN® requires three accelerometers and three ring laser gyros, which leads to a solution that becomes cost prohibitive. Another solution is to use a global positioning system which can be specially configured to output azimuth, but is not as accurate and requires connection to satellites which can be spoofed or jammed. Therefore there exists a need for a small lightweight man portable north-finder for use in accurately firing mortar rounds.